The Value and Risk of Probabilistic Thermal Uprating Scenarios on Power System Reliability

  • Chomba Tumelo-Chakonta

Student thesis: Phd


According to the European Network of Transmission System Operators for Electricity (ENTSO-E) there is a need to invest 104 billion Euros to either refurbish or construct overhead lines (OHLs). This massive enterprise is mainly driven by the need to accommodate the proliferation of renewable energy generation projects across Europe in response to the European Commission's directive to supply 20% of its energy from renewables by the year 2020. However, 30% of transmission projects experience delays; and moreover, it has been found that if the existing grid capacity is to be increased by about 1.3% it would facilitate about 3% of renewables. Therefore, attention towards the thermal uprating of existing networks has attracted research interest. In this thesis, the main contribution to this research is a probabilistic and holistically integrated system and OHL plant reliability centred thermal uprating evaluation methodology. This methodology is designed to aid the facilitation of the thermal uprating's of existing lines, through a variety of multistage and multifaceted risk based decisions. These multifaceted aspects are subject to the conflicting views to thermal uprating which stem from various utility personnel; which further stem from their constricted views on system reliability. For example, plant maintainers may resist thermal uprating because it may require the need to increase maintenance works on right-of-ways, or because they may need to prevent conductors from ageing sooner than initially projected. However, restricting thermal uprating for these reasons will limit the capability of the system to facilitate renewables, and this will negatively affect overall system reliability. Therefore, the presented methodology aids to facilitate highly efficient interdependent decision making amongst plant designers and maintainers, and system planners and operators, to effectively manage thermal uprating risks in consideration to the overall utility's goals. This thesis implements a variety of studies to enlighten utility personnel of the possible economic benefits and risk mitigation practices that could be realised through thermal uprating. To present robustly conclusive and compelling results, these studies research the value of thermal uprating from three possible time scales: long-, medium- and short-term time domains. Consequently, planners (through this methodology) will for the first time ascertain the true value of (1) uprating existing conductors by accepting the subsequent acceleration of their ageing, (2) selecting the optimal reconductoring technology from a suite of candidate (conventional and novel) conductor technologies, (3) the retensioning policy to implement (at a particular stage of a project) in order to maintain reliability, and (4) novel real-time OHL ageing management tools for power system operators to use reliably.
Date of Award1 Aug 2016
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorKostas Kopsidas (Supervisor)


  • Thermal Rating
  • Power System Reliability

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